1. Field of the Invention
The present invention relates to cleaning liquid which is used for eliminating an image formed on a recording medium in order to permit the recording medium serviceable again as a recording medium for image reproduction.
2. Description of the Prior Art
Techniques of recording an image on a recording medium by the use of an image forming material, have been widely used as an intelligence communication means. For example there have been known copying machines, printers, facsimiles and the like, in which an image is reproduced by fixing an image forming material, i.e., toner, on a recording medium, i.e., ordinary paper or transparent resin film (OHP sheet) by the help of electrophotographic techniques, and also known an ink-jet printer and the like in which an image is reproduced by an image forming material like water-soluble or oil-soluble ink on a recording means as above mentioned. Thus obtained images are usually required to have such properties as not to deteriorate even after a long-term preservation so that the image forming material which is forming an image is made to strongly adhere to the recording medium. The most commonly used recording medium is paper like ordinary paper and paper has a network structure where pulp fibers are tangled with each other complicatedly. As a result the image forming material also tangles with the network structure to form a very firm adhesion. Particularly when an image reproduction is done on an ordinary paper by the use of an image forming material containing resin component such as toner and the like, the resin component will permeate deeply into fiber of the ordinary paper because of the applied pressure or heat, which yields an extremely strong adhesion.
Meanwhile it has been proposed recently to recycle the above mentioned recording medium as a resource from the view point of an environmental protection. For instance, the ordinary paper is made from pulp and although such recycling method of paper is well-known that: the ordinary paper having a recorded image thereon is dissolved as it is or after being subjected to a shredder, into a fibrous state to separate the image forming material from fiber, and then thus separated image forming material is discharged out of the apparatus by means of a floatater or washing apparatus and thereafter the fiber is bleached followed by treatments in paper manufacturing process to yield a reclaimed paper. In this method, however, the process becomes very complicated and requires a great quantity of chemicals, water and energy, etc. In other words the process has been confronting environmental and economical troubles.
Further thus reclaimed paper has been suffering from such problems that: it shows poor toughness and tensile strength because of finely cut fiber in the reclaiming process, and for this reason paper powder is likely to be generated during a new image reproduction process, resulting in such unfavorable influences on the recording medium incorporated in a copying machine and the like as shortening of serviceable period of, for example, developer and photosensitive material; and that the image forming material separated during the reclaiming process may adhere again to the fiber so that the reclaimed paper will not be provided with sufficient whiteness.
To solve such problems a recycling method may be proposed wherein an image is eliminated in a cleaning process free from cutting of the recording medium on which the image is recorded. But the adhesion of the image forming material to the recording medium is often very firm. Particularly when paper like ordinary paper is used as a recording medium it is difficult to provide cleaning liquid capable of attaining sufficient cleaning effect because of the network structure of pulp fiber. Namely, even when the image forming material on a paper surface is subjected to cleaning, the network structure will retain the image forming material within its inside. Therefore cleaning liquid which simply dissolved the image forming material can not remove the remaining image forming material sufficiently.
Further in case that the recording medium is for purposes of Overhead Projector (OHP) sheet, the surface thereof is often coated with a resin layer which is adhesive to the resin component of the toner, which provides an extremely strong fixation. Thus it has been very difficult to remove toner by the conventional cleaning liquid.
Japanese Patent Laid-Open No. Hei 4-356089 discloses a recycling method in which toner, which is an image forming material, is permitted to contain specific material such as bio-degradable plastic and photodegradable plastic, etc., and the recording paper printed by such toner is reclaimed.
The recycling method as above, however, can be applicable only to the recording paper printed by the toner which contains specific material as bio-degradable plastic and photo-degradable plastic. In general toners commonly used in copying machines and printers, etc., at present seldom contain a specific material as above. Therefore the art disclosed in the above Laid-Open Patent is hardly adoptable in reclaiming the recording paper which bears records thereon and is wasted in great amounts. So it can be said that the art lacks universality.